As a conventional hydraulic oil temperature control system for hydraulically-driven equipment, there is the system disclosed in Patent Document 1. This conventional technology is applied to hydraulically-driven equipment of a construction machine having an engine, a hydraulic pump, a hydraulic actuator, a directional control valve, a return passage to a hydraulic oil reservoir, and an oil cooler arranged in the return passage, is comprised of a non-cooling passage bypassing the oil cooler arranged in the return passage, a flow rate control valve, specifically a solenoid on/off valve arranged in the non-cooling passage to control a flow rate of hydraulic oil flowing through the non-cooling passage, a control unit for outputting a control signal to control the solenoid on/off valve, and a temperature sensor for sensing the temperature of the hydraulic oil on an upstream side of the oil cooler, and controls the solenoid on/off valve based on the oil temperature sensed by the temperature sensor. By opening or closing the solenoid on/off valve to change flow division between a cooling passage and the non-cooling passage, the amount of heat radiation from the oil cooler is controlled.